Correct.
There are two big knocks on home schooling -- kids don't learn how to socialize with other kids, and parents' intellectual blind spots are reproduced in the next generation. Many home school parents actually recognize the former problem and enroll their kids in after school activities like sports at the schools, and that certainly helps. Also, kids from home school families seem to inevitably also belong to church groups, scouting, etc, so they do learn to interact.
The latter problem is the big one, particularly since it is the express purpose of a lot of home schooling -- it is a methodical attempt to "protect" (i.e., censor) their children from "negative" (i.e., unorthodox) influences. But I would say in the event what happens is probably much like what happened in, say, Catholic schools. For the incurious children it doesn't matter. The curious children will find their own way, and probably enjoy the "forbidden" knowledge ten times as much. Censorship may breed 95% docile and controlled sheep, but those 5% who rebel -- look out, they're on a mission!
Also, the girls get wild. Granted, some of them will fall for John Cale, but it's just a phase, and the SCA needs new blood.
Truth may be one of those things that it helps if you have to overcome something to get to it. What you work for is that much more precious.
So, basically, I think home schooling helps subpar and average kids, and it probably doesn't hurt talented kids -- it may even give them a context for rebellion against the parochialism of their upbringing.